Final Jeopardy Question

Energy

500

100200300400

Gravity

500400300200100

Forces

500400300200100

Mix

100200300400500

A 10kg ball is dropped from a height of 5m. It lands on a spring (k=100N/m). 175 J are lost as friction in the fall. When the ball is moving 5m/s, how far is the spring compressed?

Back

GPE before hand = 10kg*10m/s/s*5m = 500JTE = 500J – 175J = 325J KE after = ½ 10kg (5m/s)2 = 125JSPE after = 325J – 125J = 200J200J = ½ * 100N/m (x) 2

X2 = 200J / 50N/m = 4m2

X = 2m

A 20kg ball is moving 20m/s when it rolls up a hill. How far up the hill does the ball make it?

Back

KE = ½ 20kg * (20m/s) 2 = 4000JGPE after = 4000J = 20kg * 10m/s/s * hh= 4000J/(20kg*10m/s/s)h = 4000J/200kgm/s/sh= 20m

A 5kg ball is falling 10m/s at a height of 12 m and lands on a spring (k=150N/m). How far does the spring compress?

Back

KE = ½ * 5kg * (10m/s) 2 = 250JGPE = 5kg * 10m/s/s * 12m = 600JTotal energy = 850J

SPE = 850J = ½ 150N/m (x) 2

X2 = 850J / 75N/m = 11.33 m2X= 3.36m

A 15kg ball is compressed in a spring (k=100N/m) 3m. How high in the air will the ball make it?

Back

SPE = ½ 100N/m (3m) 2 = 450J

GPE = 450J = 15kg * 10m/s/s * h

h = 3m

A 10kg ball is at a height of 50m and moving 10m/s. How much total energy does it have?

Back

TE = KE + GPE = ½ * 10kg * (10m/s) 2 + 10kg * 10m/s/s * 50m

500J + 5000J= 5500J

Back

A scale records 100kg person’s weight on an elevator as being 200N. Which

direction and at what rate is the elevator accelerating?

Fdown = 100kg* 10m/s/s = 1000NFup = 200N

Fnet = 800N downA = Fnet/m = 800N/100kg = 8m/s/s down

A 75kg person is accelerating upwards on an elevator 4m/s/s. What weight would a scale say they weigh?

Back

Fnet = m*a = 75kg * 4m/s/s = 300N upFdown = 75kg*10m/s/s = 750N

Fup = 1050N

Back

A 20kg mass is hanging (not accelerating) from a spring (k=200N/m). How far does the

spring stretch?

Fdown = 20kg*10m/s/s = 200NFup = 200N = 200N/m * x

X = 1m

A mass is stretching a spring (k=175N/m) 2m. What must be its mass?

Back

Fup = 175N/m * 2m = 350NFdown = 350N = 10m/s/s * m

m = 35kg

Draw the FBD for a 10kg mass stretching a spring

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You have 4x as much mass as normal, but are 3x as far from the center of the Earth. What happens to the force of gravity

4x as much because of your mass, but 1/9th because of your distanceSo 4/9ths

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The acceleration of a 5kg person on Planet Physics is 100m/s/s. What is the weight of a 20kg dog on Physics

Back

Weight = Fg = m * g= 20kg * 100m/s/s = 2000N

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Any object on Physics will accelerate at a greater rate

Planet Physics is 3x as big as Earth. Which accelerates at a greater rate, a 30kg mass on Earth, or a 10kg mass on Physics?

An object has a weight of 30N. What is the mass?

Back

30N/10m/s/s = 3kg

A satellite is twice the distance from the center of the Earth. What is it’s acceleration?

10m/s/s /4 = 2.5m/s/s

Back

A 5kg mass is accelerating downwards 5m/s/s while attached to a spring (k=5N/m). How far is the spring

stretched?

Back

Fnet = 5m/s/s * 5kg = 25N down

Fg = 5kg *10m/s/s = 50N downFs = 25N up

25N = 5N/m*xX = 5m

An 5kg object stretches a spring (k=40N/m) 5m. Which way and at what rate does the object accelerate?

Back

Fup = 40N/m * 5m = 200NFdown = 5kg * 10m/s/s = 50NFnet = 150N upa = 150N/5kg = 30m/s/s

A 5kg object stretches a spring 5m. What is the spring constant? How much

SPE does the object have?

Back

K = F/x = 5kg*10m/s/s / 5m = 10N/mSPE = 1/2kx2 = ½ 10N/m * (5m) 2

SPE = 125J

A 5kg object is on top of a 10m hill. At the bottom it is moving 10m/s/s. How much energy was lost as friction?

Back

GPE = 5kg * 10m/s/s * 10m = 500JKE at bottom = ½ 5kg * (10m/s) 2 = 250JEnergy lost = 250J

What does it mean to have a large spring constant?

Back

It takes a large force to stretch the spring

Name and define as many physics terms from this unit as you can

Force, GPE, KE, SPE, Spring Force, Weight, Mass, Acceleration, Net Force, Velocity, Spring Constant, Gravity, Conservation, etc.

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